National Weather Service United States Department of Commerce

The National Weather Service (NWS) continues to monitor the accumulation of snow in the Arkansas and Rio Grande river basins. The amount of water contained in the snowpack is measured in Snow-Water Equivalent (SWE).  This is basically a translation of how much water would be produced by melting all the snow.  The primary source of these data is the U.S. Department of Agriculture’s Natural Resource Conservation Service (NRCS) SNOTEL network of monitoring stations.

Each month, the NRCS and/or the NWS River Forecast Centers produce water supply forecasts for key points in the drainage systems across the state of Colorado. These forecasts are issued early each month from January to June.  They rely heavily on the SWE data gathered by the NRCS.

This year, our snowpack in the Arkansas and Rio Grande river basins is extremely low due to warm weather and sparse precipitation. The first graphic shows the snowpack conditions in the major river basins in Colorado as a percent of normal.  These data and this graphic are produced by the NRCS and are available at: www.wcc.nrcs.usda.gov/ftpref/data/water/wcs/gis/maps/co_swepctnormal_update.pdf

 

 

Snowpacks in the mountains of the Arkansas and Rio Grande basins are at or approaching record lows for the SNOTEL monitoring network.  The monthly water supply forecasts reflect these conditions. These forecasts are produced by the NRCS for the Rio Grande basin and by the Arkansas-Red Basin RFC for the Arkansas system. Below is a graph of the most current water supply numbers for the Arkansas River basin compared to the 30-year normal observed natural streamflow. This graphic and further information regarding water supply in the Arkansas River basin of Colorado are available at:  

www.weather.gov/abrfc/watersupply_fcst

 

 

Much like the snow water equivalent data from the NRCS, the water supply forecasts in the Rio Grande basin are at or approaching historical lows for the SNOTEL era. Forecasts for specific points in the Rio Grande basin are presented below in a graphic taken from the Colorado Water Supply Outlook Report for February 1, produced by the NRCS. The full report is available at:

https://www.wcc.nrcs.usda.gov/ftpref/states/co/wsor/borco218.pdf

 

 

Precipitation throughout southeastern Colorado is well below average especially in the Rio Grande basin. The only exception to this trend is in the area around Leadville, CO in the extreme headwaters of the Arkansas River. There, a few stations have observed near to slightly above normal water-year precipitation. Precipitation estimates in the Arkansas and Rio Grande basins, as a percent of normal, for the water-year (starting Oct. 1) are also available in the NRCS Colorado Water Supply Outlook Report for February 1.

Positive news for water supplies in the area is the relative abundance of water in the reservoirs of the Rio Grande and Arkansas basins. The water stored there may offset some of the impacts to agriculture and municipal water users and push back some of the impacts to 2019. Soils and vegetation have no such reservoirs and are already dry. This poses an increasing fire risk.  That risk will continue to grow unless the region sees a significant increase in precipitation through the winter and early spring.  The figure below shows the relative storage in all the basins in Colorado as a percent of normal. That image is available at:

https://www.wcc.nrcs.usda.gov/ftpref/states/co/resv/state/monthly/resmap.pdf